Study Tracks Harrier Migration

Wing Tags Identify where Wensum Birds Go in Winter

‘B4′ at Burton Mere nature reserve. Photo Andy Davis

2012 | Five young marsh harriers hatched on Sculthorpe Moor reserve in 2012 have had wing tags fitted as part of a long-term study of where the species travel to once they leave the area where they are born.

They joined a total so far of 32 young marsh harriers hatched from other Norfolk sites in the same season and 14 from the 2011 generation, making a total to date of 46 birds carrying distinctive lime green wing tags.

Tags are visible to the naked eye from a distance, and the individual codes can be read with binoculars or telescopes.

Older birds can be distinguished from this year’s because the 2011 harriers’ tags carried white letters and numbers, while the 2012 birds have black codes.

So far four of these 2011 birds have been sighted. One was on the Isle of Sheppy in Kent in autumn 2011, one spent the winter around Lakenheath Fen and another near Welney, both in East Anglia. The fourth was reported on the Somerset Levels during spring 2012, and possibly the same one crossed the River Severn into South Wales.

Sightings of tagged harriers can be reported here and are valuable even if details of the codes are not clear to the observer.

Hawk and Owl Trust volunteer and North West Norfolk Ringing Group member Phil Littler is carrying out the study with help from other Norfolk bird ringers. The project is being funded through generous donations made by the visitors who attended a ‘Wild About the Wensum Event’ hosted by the Pensthorpe Conservation Trust. The River Wensum flows past the reserve.

2011 | The Hawk and Owl Trust is carrying out a new study to monitor the movements of rare marsh harriers in the Wensum Valley, Norfolk.

A total of 14 young marsh harriers have been fitted with wing tags. These Norfolk birds have a lime green tag and an individual identifying combination of two letters or one letter and one number in white, with one tag per wing.

The fitting of the wing tags is done by bird ringers, who have a wealth of experience and knowledge in handling birds of all species. It is a painless experience for the birds. Eight of the tagged youngsters fledged from nests at the Hawk and Owl Trust’s Sculthorpe Moor Community Nature Reserve and another six birds from nests nearby.

Hawk and Owl Trust volunteer and bird ringer Phil Littler is carrying out the study with help from Gary Elton of the Norfolk Ornithologists Association (NOA), Ray Gribble and Allan Hale from the Wensum Valley Bird Watching Society (WVBS) and John Middleton of North West Norfolk Ringing Group (NWNRG), using funding from the Pensthorpe Conservation Trust, raised at the Wild about the Wensum events.

Marsh harriers nest at the Hawk and Owl Trusts Sculthorpe Moor Community Nature Reserve near Fakenham each year and the adults and young then leave the reserve in the autumn. For several years cameras installed on nests at the reserve have given insight to the private life of young harriers.

Data from the images is being analysed by students at Leicester University, but little is known about the birds’ movements once they leave the nest, where they go in winter and where they return to nest in the spring. Marsh harriers are migratory and are expected to fly south. However in recent years many marsh harriers have been seen along the North Norfolk coast and the Norfolk Broads in winter.

Nigel Middleton, Conservation Officer for the Hawk and Owl Trust in the Eastern Region said, “20 years ago this study would not have been undertaken. No-one would have dreamed of approaching a marsh harrier nest because they were such a rare breeding bird. Although they are still very rare, the numbers of marsh harriers now breeding in Norfolk means we are in a better position to study this bird and have been given permission by Natural England. This study will allow us to understand the following questions:

Where do these birds go once they are independent of their adults? Are they a long distant migrant, travelling into Europe and beyond, or do they stay in the local area for the winter?

Once mature, do they return to the area where they were hatched, or do they breed at completely different sites?

Once they start to breed, do they breed in their traditional reed bed habitat or in other crops such as oilseed rape?”

Members of the public can help with this study by reporting any sightings of wing tagged marsh harriers. If you see a wing tagged bird, please make a note of the letters and numbers on the wing tag – if you can see them, date, time and location (if possible an OS 6 figure grid reference) and also the sex and age of the bird – if it is possible to tell.